South Korea said on Monday no decision has been made on its joint military exercises with the United States but they should not create tension, after North Korea warned the South against holding the exercises amid signs of a thaw in relations.

South Korea and the United States regularly stage military exercises, mainly in the spring and summer, but North Korea has long responded with scathing criticism, calling them a rehearsal for war.

Kim Yo Jong, the sister of North Korean leader Kim Jong Un and a senior official of the ruling Workers’ Party, warned the South on Sunday that holding the drills would undercut efforts to rebuild relations.

Her warning came days after the two Koreas restored hotlines that Pyongyang severed a year ago, as Kim and South Korean President Moon Jae-in are seeking to repair strained ties and resume summits.

Seoul’s defence ministry said on Monday that Seoul and Washington were in talks over the drills but no decision has been made.

“We have nothing to comment on her statement, but regarding the exercises, the timing and method were not finalised,” ministry spokesman Boo Seung-chan told a briefing.

The allies will decide after considering COVID-19, joint defence posture, planned transfer of wartime operational control, and the issue of “supporting diplomatic efforts for establishing lasting peace on the Korean peninsula,” Boo added.

Lee Jong-joo, spokeswoman of the Unification Ministry, which handles inter-Korean affairs, said the exercises should not be a “source of military tension in any case”, without elaborating.

The exercises have been scaled back in recent years to facilitate talks between North Korea and the administration of former U.S. President Donald Trump aimed at dismantling Pyongyang’s nuclear and missile programmes in return for U.S. sanctions relief.

But the negotiations stalled following a failed second summit in 2019 between Kim and Trump.

The coronavirus pandemic also had an impact on the drills, with the allies focusing instead on computerised simulations and minimising live field training, without mobilising U.S.-based troops.

A high-level Unification Ministry official said on Friday that the exercises should be postponed to help restart nuclear talks, but Lee declined to comment when asked if the ministry plans to make a formal recommendation.

Lee said the South last week proposed setting up a video conference system to expedite inter-Korean dialogue and approved plans by two civilian relief groups to send humanitarian aid to the North.

Reuters